Heretofore, as a method for analyzing biological fluids, an analyzing method using a micro device wherein a liquid flow path is formed has been known. Since the micro device can control fluids using a rotating device, and can perform the measurement of samples, the separation of cytoplasmic materials, and the transportation and distribution of separated fluids using centrifugal force, various biochemical analyses can be performed.
An example of methods for measuring samples using centrifugal force is the method disclosed in Japanese Patent Laid-Open No. 61-167469. FIG. 9 shows this analytical device.
The analytical device is equipped with a central accommodating section 71 for accommodating a liquid to be diluted before analysis, a volume measuring chamber 72 and an overflowing chamber 73, a mixing chamber 74, and measuring cells 75 from the center of the analytical device toward the periphery. The volume measuring chamber 72 is located in substantially parallel with the overflowing chamber 73, and an opening 78 is formed on the wall of the volume measuring chamber facing a supplying port 76 in addition to the supplying port 76 and an overflowing port 77. The opening 78 is always open, and has a cross section much smaller than the cross sections of the supplying port 76 and the overflowing port 77.
With such a configuration, the volume measuring chamber 72 can be quickly filled, and the overflow can be immediately removed. When the volume measuring chamber 72 starts to be filled with a liquid, the liquid immediately starts flowing out of the chamber. Therefore, since the ratio of “supplying time,” to “flow-out time from the flow-out port”, which is a function of the ratio of “cross-sectional area of the flow-in port” to “cross-sectional area of the flow-out port”, can be reduced, accuracy is added to measurements.
In National Publication of International Patent Application No. PCT/US91/03840, which was published as WO91/18656, an analytical device shown in FIG. 10 is disclosed.
The analytical device has a fluid chamber 61, a volume measuring chamber 82 connected to the fluid chamber 81 and disposed outside the fluid chamber 81 in the radial direction, an overflowing chamber 83 connected to the volume measuring chamber 82, a receiving chamber 84 disposed outside the volume measuring chamber 82 in the radial direction, and a capillary connector 85 for supplying a liquid to the receiving chamber 84 from the volume measuring chamber 82. The capillary connector 85 has a siphon 86 having a capillary structure. Since the capillary force is smaller than the centrifugal force when the analytical device is rotationally in operation by locating the elbow-shaped bend of the siphon 86 so as to have substantially the same distance as that from the center of the analytical device to the innermost point of the volume measuring chamber 82 in the radial direction, the liquid/air interface coincides with the shape of a rotating cylinder having the same axis line as that of the volume measuring chamber 82, and also having a radius of a length equal to the distance from the center of the analytical device to the innermost point of the volume measuring chamber 82 in the radial direction, the chamber 82 is filled, and the excessive liquid flows into the overflowing chamber 83. When the operation of the analytical device is stopped, the liquid filled in the volume measuring chamber 82 flows into the capillary connector 85 by the capillary force, and when the analytical device is rotated again, the siphon is activated, and the liquid present in the volume measuring chamber 82 is discharged into the receiving chamber 84.